Antarctic Automatic Weather Station Datafor the calendar year

1996

by

Linda M. KellerGeorge A. WeidnerCharles R. Stearns

Matthew T. WhittakerRobert E. Holmes

Space Science and Engineering CenterUniversity of Wisconsin

1225 W. Dayton St.Madison, Wisconsin

February 1998

Antarctic Automatic Weather Station Data

for the calendar year

1996

by

Linda M. Keller

George A. Weidner

Charles R. Stearns

Matthew T. Whittaker

Robert E. Holmes

Space Science and Engineering CenterUniversity of Wisconsin

1225 W. Dayton St.Madison, Wisconsin

February 1998

TABLE OF CONTENTS

Page

1. Introduction......................................................................................................................................... 1

2. Data Transmission............................................................................................................................. 1

3. AWS Identification and Location...................................................................................................... 1

4. AWS Data Summaries...................................................................................................................... 8

4.1 Monthly Data Summaries............................................................................................................. 8D-10............................................................................................................................................. 9D-47............................................................................................................................................. 9D-57............................................................................................................................................. 9D-80............................................................................................................................................. 9Dome C II.................................................................................................................................... 9Port Martin................................................................................................................................ 10Cape Denison........................................................................................................................... 10Penguin Point........................................................................................................................... 10Sutton........................................................................................................................................ 11Cape Webb............................................................................................................................... 11

Byrd Station.............................................................................................................................. 11Mount Siple............................................................................................................................... 12Harry......................................................................................................................................... 12J.C. ............................................................................................................................................ 12Theresa..................................................................................................................................... 13Doug.......................................................................................................................................... 13Brianna...................................................................................................................................... 13Elizabeth................................................................................................................................... 14Erin............................................................................................................................................ 14Marble Point.............................................................................................................................. 14Ferrell........................................................................................................................................ 15Pegasus North.......................................................................................................................... 15Pegasus South......................................................................................................................... 15Minna Bluff................................................................................................................................ 16Linda.......................................................................................................................................... 16Willie Field................................................................................................................................. 16Whitlock..................................................................................................................................... 17Young Island............................................................................................................................. 17Possession Island.................................................................................................................... 17Marilyn....................................................................................................................................... 18Schwerdtfeger.......................................................................................................................... 18Gill............................................................................................................................................. 18Lettau........................................................................................................................................ 19Elaine........................................................................................................................................ 19

Manuela...................................................................................................................................... 19Lynn........................................................................................................................................... 20Larsen Ice Shelf....................................................................................................................... 20Butler Island.............................................................................................................................. 20Uranus Glacier.......................................................................................................................... 21Racer Rock................................................................................................................................ 21Bonaparte Point........................................................................................................................ 21Ski-Hi......................................................................................................................................... 21Santa Claus Island................................................................................................................... 22Limbert..................................................................................................................................... 22AGO-A84................................................................................................................................... 22Clean Air (South Pole)............................................................................................................. 23Nico........................................................................................................................................... 23Henry........................................................................................................................................ 23Relay Station............................................................................................................................ 24Dome Fuji................................................................................................................................. 24

4.2 Three Hourly Data Summaries................................................................................................. 25

5. AWS Calibration................................................................................................................................. 26

5.1. Temperature............................................................................................................................... 26 5.2. Pressure...................................................................................................................................... 26 5.3. Wind Direction and Speed........................................................................................................ 26 5.4. Relative Humidity....................................................................................................................... 27 5.5. Vertical Air Temperature Difference........................................................................................ 27

6. AWS Operations Summary for 1996................................................................................................ 27

6.1. AWS Performance..................................................................................................................... 27 6.2. AWS Antarctic Field Activities.................................................................................................. 30

7. Global Telecommunications System................................................................................................ 32

8. Data and Field Report Availability.................................................................................................... 32

9. Acknowledgments............................................................................................................................. 34

1. INTRODUCTION

A network of automatic weather station (AWS) units is deployed to collect Antarctic surface weather observations in support of specific meteorological research projects as well as operational activities at McMurdo. The 1996 network consisted of 51 installed AWS units providing observations on the Ross Ice Shelf, east of the Transantarctic Mountains and north of McMurdo to the Adelie Coast, along the Antarctic Peninsula and climatological locations such as the South Pole. Each unit measures air temperature, wind speed, and wind direction normally at the top of the unit's tower at a nominal height of three meters and air pressure at the electronics enclosure (Figure 1). Some AWS units also measure the relative humidity at three meters and vertical air temperature difference between 0.5 and 3 meters. Measurement heights relative to the actual surface at the site are nominal due to snow accumulation around the AWS unit.

2. DATA TRANSMISSION

The transmitted AWS data are received and stored by the ARGOS data collection system on the NOAA series of polar orbiting satellites. The data are retransmitted by the satellite for reception by a local user terminal (LUT) as at McMurdo, Antarctica. The data are processed into scientific units and are available for local use. The complete data set is received daily at Madison, Wisconsin, from Service ARGOS, Toulouse, France, for processing and distribution to the users.

3. AWS IDENTIFICATION AND LOCATION

Site location is defined by the latitude and longitude which is determined by various methods: sun shots, angles to geographical features, aircraft data, ice breaker data, the platform location system of Service ARGOS, and the Global Positioning System. AWS elevation is obtained by barometry and should be correct to within +/- 5 meters. Site names were introduced for convenience. Table 3.1 lists the site name, ARGOS identification number, latitude, longitude, elevation, start date for the site, and the World Meteorological Organization (WMO) number for the site. Figures 2, 3, 4, and 5 show the locations of the AWS units in the Antarctic for 1996.

The ARGOS identification number (ID) is used to identify the data sets distributed to the users. AWS units are sometimes moved from one location to another, and as a result, the ID at a given site may change from year to year. Table 3.2 lists the site name with the ARGOS ID, the site start date, and the ID start and stop dates.

Figure 1. Layout of the AWS unit used in the Antarctic. The installed AWS unit has a 3-meter tower with a horizontal boom supporting the antenna, aerovane for measuring wind speed and direction, air temperature resistance thermometer, upper thermopile for measuring vertical air temperature difference, and the relative humidity sensor. The electronics enclosure is mounted at the mid point of the tower. The gel cell batteries are placed at the tower base. The solar panel, located near the tower top, faces north.

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Table 3.1AWS site name, geographic location and elevation, site start date, and WMO number for 1996. Site name ARGOS ID Lat. (Deg) Long. (Deg) Elev. (m) Site Start Date WMO No.

Adelie LandD-10 #8919 66.71oS 139.83oE 243 08 Jan 80 89832D-47 #8986 67.40oS 138.73oE 1560 24 Jan 83 89834D-57 #21360 68.20oS 137.54oE 2105 16 Jan 81D-80 #8916 70.04oS 134.88oE 2500 14 Jan 83 89836Dome C 8904 74.50oS 123.00oE 3280 05 Feb 80 89828Dome C II 8989 75.12oS 123.37oE 3250 12 Dec 95 89828Port Martin 8930 66.82oS 141.40oE 39 19 Jan 90Cape Denison 8907 67.01oS 142.66oE 31 20 Jan 90Penguin Point 8929 67.62oS 146.18oE 30 24 Dec 92 89847Sutton 8939 67.08oS 141.37oE 871 26 Dec 94Cape Webb 8933 67.93oS 146.82oE 37 28 Dec 94

West AntarcticaByrd Station 8903 80.00oS 119.40oW 1530 05 Feb 80 89324Mount Siple 8981 73.20oS 127.05oW 230 20 Feb 92 89327Harry 21355 83.00oS 121.39oW 945 29 Nov 94J.C. 21357 85.07oS 135.52oW 549 29 Nov 94Theresa 21358 84.60oS 115.81oW 1463 29 Nov 94 89314Doug 21359 82.32oS 113.24oW 1433 29 Nov 94Brianna 21362 83.89oS 134.15oW 549 30 Nov 94Elizabeth #21361 82.61oS 137.08oW 549 30 Nov 94 89332Erin #21363 84.90oS 128.81oW 1006 29 Nov 94

Ross Island RegionMarble Point 8906 77.44oS 163.69oE 120 05 Feb 80 89866Ferrell 8934 77.93oS 170.82oE 45 10 Dec 80 89872Pegasus North 8927 77.95oS 166.51oE 10 23 Jan 90 89667Pegasus South 8937 77.99oS 166.58oE 10 14 Jan 91Minna Bluff 8988 78.55oS 166.66oE 920 22 Jan 91 89768 Linda #8909 78.48oS 168.38oE 50 21 Jan 91 89769Willie Field 8901 77.87oS 167.02oE 20 25 Jan 92

Ocean IslandsWhitlock 8921 76.14oS 168.39oE 274 23 Jan 82 89865Scott Island 8983 67.37oS 179.97oW 30 25 Dec 87 89371Young Island 8980 66.23oS 162.28oE 30 01 Jan 91 89660Possession Is. 8984 71.89oS 171.21oE 30 29 Dec 92 89879

Ross Ice ShelfMarilyn 8931 79.95oS 165.13oE 75 16 Jan 84 89869Schwerdtfeger 8913 79.90oS 169.97oE 60 24 Jan 85 89868Gill 8911 79.99oS 178.61oW 55 24 Jan 85 89376Lettau 8908 82.52oS 174.45oW 55 29 Jan 86 89377Elaine 8900 83.13oS 174.17oE 60 28 Jan 86 89873

Reeves GlacierManuela 8905 74.95oS 163.69oE 80 06 Feb 84 89864Lynn 8935 74.21oS 160.41oE 1772 19 Jan 88 89860

Antarctic PeninsulaLarsen Ice 8926 66.95oS 60.91oW 17 21 Oct 85 89262Butler Island 8902 72.21oS 60.17oW 91 01 Mar 86 89266Uranus Glac. 8920 71.43oS 68.93oW 780 06 Mar 86 89264Racer Rock 8947 64.07oS 61.61oW 17 15 Oct 89 89261Bonaparte Pt. 8912 64.78oS 64.07oW 8 05 Jan 92 89269Recovery Glcr. 8932 80.82oS 22.26oW 1220 18 Jan 94Ski-Hi 8917 74.98oS 70.77oW 1395 21 Feb 94 89272Santa Claus Is 8910 64.96oS 65.67oW 25 10 Dec 94Limbert 8925 75.42oS 59.95oW 40 30 Nov 95 89257AGO-A84* 8932 84.36oS 23.86oW 2103 09 Jan 96

High Polar PlateauClean Air 8987 90.00oS 2835 29 Jan 86 89208 Nico 8924 89.00oS 89.67oE 2935 26 Jan 93 89799Henry 8985 89.01oS 1.30oW 2755 26 Jan 93 89108Relay Station 8918 74.02oS 43.06oE 3353 01 Feb 95 89744Dome Fuji 8982 77.31oS 39.70oE 3810 08 Feb 95 89734

# New ARGOS ID for 1996 at the site; *New location for 1996

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Figure 2. Antarctic automatic weather station locations during 1996 identified by the site name. Area around Ross Island is shown in Figure 3. Adelie Coast area is shown in Figure 4.

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Figure 3. Location of Antarctic automatic weather stations in the vicinity of Ross Island, Antarctica during 1996.

Figure 4. Location of Antarctic automatic weather stations on the Adelie Coast during 1996.

Table 3.2

1996 Antarctic AWS site name, ARGOS identification number (ID), site start date, ID start date, and ID stop date if occurring in 1995.

Site ARGOS ID Site Start Date ID Start Date ID Stop DateD-10 21364 08 Jan 80 25 Dec 95 21 Jan 96

8919 21 Jan 96D-47 8986 24 Jan 83 11 Feb 96D-57 21360 16 Jan 81 08 Feb 96D-80 8919 14 Jan 83 12 Dec 85 24 Jan 96

8916 24 Jan 96Dome C 8904 05 Feb 80 05 Feb 80 02 Jan 96Dome C II 8989 12 Dec 95 12 Dec 95Port Martin 8930 19 Jan 90 23 Dec 92Cape Denison 8907 20 Jan 90 27 Dec 94Penguin Point 8929 24 Dec 92 24 Dec 92Sutton 8939 26 Dec 94 26 Dec 94Cape Webb 8933 28 Dec 94 28 Dec 94Byrd Station 8903 05 Feb 80 05 Feb 80Mount Siple 8981 20 Feb 92 20 Feb 92Brianna 21362 30 Nov 94 30 Nov 94Elizabeth 21356 30 Nov 94 30 Nov 94 17 Jan 96

21361 17 Jan 96J.C. 21357 29 Nov 94 29 Nov 94Erin 21361 29 Nov 94 29 Nov 94 18 Jan 96

21363 18 Jan 96Harry 21355 29 Nov 94 29 Nov 94Theresa 21358 29 Nov 94 29 Nov 94Doug 21359 29 Nov 94 29 Nov 94Marble Point 8906 05 Feb 80 05 Feb 80Ferrell 8934 10 Dec 80 10 Dec 80Pegasus North 8927 23 Jan 90 23 Jan 90Pegasus South 8937 14 Jan 91 14 Jan 91Minna Bluff 8988 22 Jan 91 12 Jan 94Linda 8909 21 Jan 91 24 Nov 95Willie Field 8901 25 Jan 92 25 Jan 92Whitlock 8921 23 Jan 82 23 Feb 94Scott Island 8983 25 Dec 87 27 Dec 92Young Island 8980 01 Jan 91 01 Jan 91Possession Island 8984 29 Dec 92 29 Dec 92Marilyn 8931 16 Jan 84 18 Jan 91Schwerdtfeger 8913 24 Jan 85 22 Jan 93Gill 8911 24 Jan 85 25 Jan 91Elaine 8900 28 Jan 86 23 Jan 93Lettau 8908 29 Jan 86 29 Jan 86Manuela 8905 06 Feb 84 15 Feb 87Lynn 8935 19 Jan 88 23 Jan 92Larsen Ice Shelf 8926 21 Oct 85 01 Jan 86Butler Island 8902 01 Mar 86 01 Mar 86Uranus Glacier 8920 06 Mar 86 24 Jan 92Limbert 8925 30 Nov 95 30 Nov 95Racer Rock 8947 15 Oct 89 08 Dec 91Bonaparte Point 8912 05 Jan 92 05 Jan 92Recovery Glacier 8932 18 Jan 94 18 Jan 94 09 Jan 96AGO-A84 8932 09 Jan 96 09Jan 96Ski-Hi 8917 21 Feb 94 21 Feb 94Santa Claus Island 8910 10 Dec 94 10 Dec 94Clean Air 8987 29 Jan 86 25 Jan 94Henry 8985 26 Jan 93 26 Jan 93Relay Station 8918 01 Feb 95 01 Feb 95Dome Fuji 8982 08 Feb 95 08 Feb 95

4. AWS DATA SUMMARIES

The data received by the University of Wisconsin, Space Science and Engineering Center, contain all the information received by the ARGOS system including duplicate and erroneous transmissions. Invalid data are eliminated during a quality check, and the valid data are converted to scientific units producing the complete data set. Data selected at three hourly intervals, plus or minus one hour, produce a three hourly data set for each AWS unit month. Section 6.1, AWS Performance, provides some explanations for missing and invalid data.

Use of the 1996 Antarctic AWS data for publication should acknowledge the support of NSF-OPP Grant 9303569 and 9419128 or reference this publication.

4.1 Monthly Data Summaries

The monthly summaries consist of the monthly means, from the three hourly data set, and the extremes, from the complete data set. For monthly values to be included, 25% of the three hourly observations must be available. Months with 50-75% of data missing occur most often when a station is started or stopped in the middle of the month. This can cause a bias in the monthly mean, especially during seasons when parameters such as temperature change rapidly. Annual means are calculated only when twelve months of data are available. The data are presented in the same order as the sites listed in Table 3.1. Definitions of the monthly data summary headings are listed below.

Heading Definition Mean air temperature, oC. Mean value for the month.

Percent of monthly data missing. Ratio of the number of missing observations to the number of possible observations X 100.

Maximum air temperature, oC. Maximum value for the month.Minimum air temperature, oC. Minimum value for the month. Mean wind speed, m/s. Mean value for the month.

Percent of monthly data missing. Ratio of the number of missing observations to the number of possible observations X 100.

Resultant wind speed, dir/vv. Resultant speed and direction for the month.Constancy. Ratio of the monthly resultant to the monthly mean wind

speed.Maximum wind speed, dir/vv. Maximum wind speed and direction for the month. Mean air pressure, mb. Mean value for the month.

Percent of monthly data missing. Ratio of the number of missing observations to the number of possible observations X 100.

Maximum air pressure, mb. Maximum value for the month.Minimum air pressure, mb. Minimum value for the month.

4.2 Three Hourly Data Summaries

The data set for each AWS unit for the month is scanned to pick out the nearest observation within one hour of the UTC hours 00, 03, 06, 09, 12, 15, 18, and 21 to produce the three hourly data set. If valid data are not available within the three hourly time interval, then the entry is left blank to indicate missing data. The means, standard deviations, resultant wind speed and direction, the distribution of temperature, and wind speed with wind direction are determined from the three hourly observations and are presented as a monthly summary at the bottom of each page. A wind direction value of zero indicates a wind speed less than 0.50 m s-1. North is indicated by a value of 360 degrees. The maximum and minimum values are taken from the complete data set, not the three hourly data set. The appropriate monthly data from the three hourly data set are used for the monthly summaries presented in 4.1. In the presence of sunlight the air temperatures are questionable if the wind speed is less than 1 m s-1. These summaries are available by anonymous FTP (see Section 8). If you are unable to access the Internet, we will send the information either on diskettes or paper. Please contact us for further information (the address is at end of Section 8).

5. AWS CALIBRATION

5.1. Temperature

The external and internal temperatures are calibrated using a 1000 ohm 0.05% resistor in place of the platinum resistance thermometers which are 1000 ohms resistance at 0oC. Because the other resistances in the temperature circuit are known only to 1%, the temperature calibration will vary from one electronic unit to another. The correction factor determined from the calibration resistor is programmed into the read-only-memories for each unit. After the correction factors have been programmed into the AWS, a calibration box with 0.1% resistors is used in the field to check the temperature calibration.

5.2. Pressure

The atmospheric pressure transducer is a Parascientific model 215A digiquartz pressure gauge. The transducer frequency changes from a nominal 40 kHz at zero pressure to a nominal 36 kHz at 1000 hPa. The pressure resolution is approximately 0.05 hPa. Paulin aneroid barometers calibrated against a mercury barometer of 10 mm bore are used to check the pressure gauge calibration. Comparisons are made between AWS units, a Parascientific Model 760-16B accurate to +/- 0.1 hPa, and with the mercury barometers at Scott Base, Antarctica. The calibrations should be within +/- 0.2 hPa. Two mercury barometers have been purchased for use at McMurdo, Antarctica but are not yet available. The reference vacuum on the older pressure transducers can degrade with time with a maximum observed 4 hPa shift to lower pressure after ten years. Recalibration of each pressure transducer would be desirable when each unit is serviced.

5.3. Wind direction and Speed

The Belfort model 123 aerovane measures wind direction and speed. The aerovane rotates a potentiometer wiper, and the fraction of full scale of the potentiometer is measured. The wind direction is checked by positioning the aerovane to the cardinal directions relative to the boom supporting the aerovane. North or the potentiometer zero is towards the antenna on the boom and has a dead zone of 5o. During the field installation the boom is usually aligned along the north-south line as determined from the sun's azimuth, longitude, and Greenwich Mean Time. In some cases the 180o end of the boom may point in a direction other than south. At Manuela site, the 180o end of the boom points up the glacier and a correction is added to the data during processing. At Byrd site the wind is usually out of the north so the boom was rotated 120o and the correction added during the data processing. The wind speed is determined from the aerovane tachometer voltage output as 0.0472 volt per meter per second. The aerovane tachometers are spun at 1800 rpm with a load of 1071.5 ohms and the output should be 9.20 +/-0.05 vdc. Three additional wind sensors were used with AWS units for 1996. These were the Vaisala anemometer model WAA-15, the R.M. Young wind monitor model 05103, and the Hydro-Tech WS-3 rotor anemometer. The Vaisala WAA-15 and the Hydro-Tech WS-3 were used as backup sensors for measuring wind speed in the Adelie Coast area. The WAA-15 is a 3-cup opto-electronic anemometer. When rotating, the anemometer produces a pulsed output that is proportional to the wind speed. Rated accuracy is +/- 2% up to 75 m/s. The pulsed output was input into one of the digital counter channels for 5 seconds. This resulted in a calibration value of .293 m/s/bit. The Hydro-Tech WS-3 is a disk rotor, 3 in. high and 12 in. overall diameter, with radial cups, and the threshold sensitivity is 3 mph. The anemometer utilizes a commercial dc tachometer generator. Output is 0 to +5 vdc (and 0 to 1 ma) over the desired full scale wind speed of 85 m/s. Accuracy is +/- 2%.

The R.M. Young monitor 05103 also used a 10000 ohm potentiometer so that the wind direction was recorded identically with the Belfort/Bendix aerovanes. The wind speed was from the range of 0 to 1.0 volt full scale corresponding to 50 m/s. Thus the calibration for wind speed was a nominal .195 m/s/bit for the R.M. Young with +/- 1% up to 50 m/s. 5.4. Relative Humidity

The Vaisala HMP-35A humidity sensor output voltage varies linearly with relative humidity (U). The sensor is calibrated by placing it over saturated salt solutions with known relative humidities at room temperature: sodium chloride (U=75%), and lithium chloride (U=12%) are used. In addition, a dry inert gas, forced past the sensor, gives a 0% U, and the sensor output can be zeroed. Then, the gain setting can be set directly using a salt solution with a high relative humidity, such as sodium chloride. The resolution of the humidity sensor is about 1% and the drift can be 2 to 3% per year in the field. The relative humidity data are not included on the summary pages but are included in the 3 hourly data sets.

5.5. Vertical Air Temperature Difference

Two junction thermocouples are used to measure the air temperature difference between 3 m and 0.5 m on the tower. The output is about 78 microvolts for 1.oC temperature difference between the junctions at 0.0oC, dropping to 60 microvolts at -80oC. Zero output is adjusted to 0.4 volts, so that 0 to 1 volt corresponds to a -6oC to +9oC range of air temperature differences between 3 m and 0.5 m. The resolution is 0.05oC. Calibration of the individual systems is done by applying known voltages to the amplifier input. The vertical temperature difference data are not included on the summary pages but are included in the 3 hourly data sets.

6. AWS OPERATIONS SUMMARY FOR 1996

6.1. AWS Performance

Fifty AWS units were installed at the start of 1996 and 51 were installed by the end of 1996. Based on the installation months the AWS units delivered 74% of the temperature data, 73% of the pressure data and 62% of the wind data during 1996. Complete data sets were received from 21 AWS units and 11 AWS units operated for the installed period. Eighteen AWS units were not received for one month or more during the year or stopped during the year.

The wind system has the poorest performance. If the wind speed is zero or the wind direction is constant for extended periods (days to months) then the data is considered invalid. The reason for this behavior is not known but is believed to be due to the build up of frost on the wind system. This usually occurs in the winter season and at several AWS sites. The wind speed is most frequently zero when the wind direction is constant. Another problem with the wind system involves the tachometer for measuring wind speed. The brushes on the Belfort aerovane quickly wear down and fill the gaps between the contacts with brush material, shorting out the tachometer output. As a result we do not know the calibration. The problem is in the construction of the tachometer, so we have begun to install a new wind system manufactured by R.M. Young. They are currently operating at Nico, Henry, Pegasus North, Minna Bluff, Willie Field, Ski-Hi, J.C., Theresa, Doug, Brianna, Elizabeth, Erin, D-47, D-57, and Bonaparte Point sites.

Site Performance

D-10 Station inadvertently removed and replaced with non-functioning station on 21 January.

D-47 Station installed 11 February. Station operated intermittently and then stopped 4 August due to low battery voltage. Temperature not functioning after early April.

D-57 Station installed 8 February. Station operated until 4 August when it stopped due to low battery voltage.

D-80 Station changed 24 January. Temperature and wind speed and direction were not reporting correctly starting in mid-February, and pressure was not reporting correctly in March. Station stopped in March due to low battery voltage.

Dome C Station stopped on 3 January due to low battery voltage. Dome C II OK.Port Martin Station transmitted sporadically from April to September due to low battery

voltage. As battery recharged, more transmissions received. A Hydro-Tech anemometer was installed instead of delta-T sensor. Pressure corrected for high wind speed conditions.

Cape Denison Intermittent transmission in May. The Belfort aerovane failed beginning in March. A Hydro-Tech anemometer was installed instead of delta-T sensor. Pressure corrected for high wind speed conditions.

Penguin Point A Vaisala anemometer was installed instead of the delta-T sensor. Wind speed from the Vaisala anemometer was substituted for the Belfort aerovane wind speed from January through November since the aerovane wind speed was not functioning properly. Pressure corrected for high wind speed conditions.

Sutton Station started running 10 January. Station stopped 20 February and started again 31 March. Occasionally missing several days of data for the rest of the year. Station stopped for most of October. A Hydro-Tech anemometer was installed instead of delta-T sensor.

Cape Webb Aerovane not operating during the year. Station stopped from 17 April to 7 June and again the first half of July. A Hydro Tech anemometer was installed instead of the delta-T sensor.

Byrd Station stopped 11 April.Mount Siple Pressure erratic in summer half of year. Site has a "dog house" AWS

without wind speed and direction.Harry Pressure erratic in summer half of year. Station operated erratically in May

and July and stopped 26 July. Station resumed transmission 21 October and operated erratically in December.

J.C. Station resumed transmitting on 18 January after power was disconnected and reconnected. Wind speed and direction not functioning. Station stopped 2 May due to low battery voltage and resumed transmitting 17 October as battery recharges in the austral spring. No humidity sensor.

Theresa Station resumed transmitting on 18 January after power supply was disconnected and reconnected. Station operated sporadically from mid-May through September. Delta-T not functioning properly mid-February to mid-November.

Doug Pressure erratic from mid-May through November. Station stopped 26 November. Delta-T not functioning properly.

Brianna Station transmitted erratically from the end of July to the beginning of October due to low battery voltage.

Elizabeth Station resumed transmitting 15 February. Aerovane operated intermittently June through September. Station transmitted erratically after 14 November.

Erin Station replaced and began transmitting 18 January. Aerovane stopped functioning 6 April. Station stopped 17 July due to low battery voltage and

resumed transmission in late September as battery recharged in the austral spring.

Marble Point OK.Ferrell OK.Pegasus North No pressure reports due to calibration problem. Relative humidity sensor

not functioning properly.Pegasus South Relative humidity sensor not functioning properly.Minna Bluff OK. Linda OK.Willie Field OK. Whitlock Intermittent wind data from April to November. Intermittent transmissions in August and September due to low battery voltage.Scott Island Sporadic transmissions. Station stopped 7 March due to low battery

voltage. Site has a "dog house" AWS without wind speed and direction.Young Island Another Adog house@ AWS without wind speed and direction installed 26

January. Station not functioning properly for three weeks in February.Possession Island Transmissions were irregular in November and December. Site has a "dog

house" AWS without wind speed and direction.Marilyn OK.Schwerdtfeger Station reinstalled 27 January. Relative humidity is erratic August-October.Gill Aerovane operated intermittently during July-November. Delta-T not

functioning properly the first part of January. Relative humidity not functioning properly the last part of January until the end of the year.

Lettau Station transmitted sporadically February-April and stopped 12 April. The station resumed transmitting 10 November

Elaine Aerovane did not function throughout the year. The delta-T sensor was not operating properly.

Manuela Aerovane was replaced on 4 February. Aerovane stopped again on 29 July.

Lynn Station stopped transmitting on 3 April and resumed on 30 April.Larsen Ice Aerovane did not operate after June.Butler Island Pressure corrected.Uranus Glacier Station stopped 13 February and resumed transmission 3 December with

one day of transmission on 31 October.Racer Rock Intermittent data transmission, very sparse from last half of May through the end of the year due to low battery voltage.Bonaparte Point New batteries installed in January. Station resumed transmission 29 January,

but the pressure was not functioning properly. Station stopped 11 July. New station electronics installed 23 December.

Recovery Glacier Station removed.Ski-Hi Intermittent data transmissions.Santa Claus Island Water temperature probe did not function due to a defective probe.

Temperature began to malfunction in May. Aerovane did not operate during June and August -September. Station stopped 28 September due to low battery voltage. New station electronics and batteries were installed 25 December. Aerovane still not functioning.

Limbert No delta-T sensor. Aerovane “frozen” most of the time from the end of February through October.

AGO-A84 Station installed 9 January. Aerovane “frozen” most of the time from the end of April through the beginning of November. Station stopped 16 July due to low battery voltage and resumed transmission 18 September as

battery recharged in the austral spring.Clean Air Pressure jumped erratically March-October.

Nico Aerovane occasionally “frozen” during the winter months.Henry Station stopped 12 September due to low battery voltage and resumed

transmission 14 October as battery recharged in the austral spring.Relay Station OK.Dome Fuji Pressure not functioning correctly.

6.2 AWS Antarctic Field Activities

Field activities for 1996 began with the arrival of Charles Stearns, Greig Thompson and Jonathan Thom at McMurdo in early January to begin repair work in the Siple Coast and Ross Ice Shelf areas. On 16 January, Stearns, Thompson, and Thom left McMurdo Station for Up Stream Bravo. On 17 January, a Twin Otter flight was made to Elizabeth site and AWS 21356 was removed and replaced with new 21361 electronics. The antenna cable did not have the shield soldered to the TNC connector. The aerovane was replaced with a Bendix aerovane, and the antenna cable was replaced with one that had the shield soldered to the TNC connector.

On 18 January, a Twin Otter flight was made to J.C. site. The power supply was disconnected and then reconnected, and the unit began to cycle normally. The malfunctioning wind direction was not checked because of the high wind speed at the time of the site visit. The flight continued on to Erin site, where the antenna cable was replaced with one that had the shield soldered to the TNC connector, but the unit still did not transmit. Because of limited resources, the electronics were not replaced at that time, and the party returned to Up Stream Bravo. A Twin Otter flight was made to Theresa site. One battery box was not connected to the junction box. The power supply was disconnected and then reconnected, and the station began to cycle normally. A second flight to Erin site was then made and AWS 21361 was replaced with 21363. A Belfort aerovane was also installed. On 19 January, Stearns, Thom, and Thompson returned to McMurdo Station.

On 23 January, a Twin Otter flight was made to Marilyn site. The site was raised by clamping two 1.8 m Rohn tower sections to the exposed 2.0 m of Triex tower using two sets of mounting bars. Three nylon rope guys were added to the tower addition. Two boxes of three gel-cell batteries were installed as well as a new power junction box and a new solar panel. The boom is now 3.8 m above the snow surface. The 1/8 in diameter antenna was replaced with a 1/4 in diameter one. On 24 January, a Twin Otter flight was made to Gill site, and the site was raised in a similar fashion as that at Marilyn.

A Twin Otter flight was made to Schwerdtfeger site on 27 January, and AWS 8913 was installed. A Bendix aerovane was installed as well as 2 boxes of three gel-cell batteries and new battery cables.

Using parts from the AWS units returned from Up Stream Bravo, AWS units 8980 and 8983 were repaired. Crew members of the USCG Polar Star installed a dog house AWS 8980 at Young Island on 26 January. Dog house AWS 8983 was not installed at Scott Island because of fog. AWS 8983 was returned to Seattle for installation during the next field season.

On the Antarctic Peninsula, members of the Long Term Ecological Research group replaced the batteries at Bonaparte Point AWS site on 14 January and installed a sea-water temperature probe at Santa Claus Island AWS site on 13 February. The sea water temperature probe did not function properly due to inadequate instrument design and manufacture. Members of Programma Nazionale di Ricerche in Antartide at Terra Nova Bay installed a Belfort aerovane at Manuela site on 4 February. The aerovane was delivered to them by the Polar Star on the refueling trip for the base.

Members of the Institut Francais pour la Recherche et la Technologie Polaires (IFRTP) removed AWS 8919 from D-80 and installed AWS 8916 in its place on 24 January. On 8 February, AWS 21360 was installed at D-57, and AWS 8986 was installed at D-47 on 11 February. Also, AWS 21364 was inadvertently removed from D-10 on 21 January. The replacement unit, AWS 8919, did not function.

In December, 1996 Tony Amos took the place of C.R. Stearns on the Polar Duke to repair the AWS units on Bonaparte Point and Santa Claus Island. At Bonaparte Point on 23 December, Amos replaced the AWS electronics, batteries, and boom. The electronic box connectors to the boom and junction box were replaced with connectors that are supposed to be capable of withstanding corrosion by salt water. The connections between the junction box and the batteries and solar panel were wired directly and the openings were plugged with modeling clay. The water temperature sensor was installed in the sea water at Bonaparte Point. The water temperature probe that was removed was severely damaged by the salt water and the action of the sea ice. At Santa Claus Island on 26 December the pipes protecting the water temperature probe were destroyed. In addition, the AWS tower was bent at the base but left in place. The replacements were similar to those at Bonaparte Point. The water temperature probe was left on the surface and not put into the water. A stop was made at Racer Rock. The AWS unit was operating intermittently but the equipment was not available to make the necessary repairs.

7. GLOBAL TELECOMMUNICATIONS SYSTEM

The data from 35 Antarctic AWS units were entered into the Global Telecommunications System (GTS) during 1995. The data are collected by Service ARGOS. As soon as the data are received, Service ARGOS processes them and sends them on to the National Weather Service which distributes the data to the GTS. The data headers are:

SMAA14 KARS YYGGgg SIAA14 KARS YYGGgg SNAA14 KARS YYGGgg

where S indicates surface, M is main observations (at 00, 06, 12, and 18 UT), I is intermediate observations (at 03, 09, 15, and 21 UT), and N is any other time. AA14 is for Antarctica, and KARS stands for the Landover receiving center (backup is LFPW for the center in Toulouse, France). YY indicates the day in the month, GG is the hour, and gg is the minutes. Table 3.1 contains the WMO # used by the GTS grouped according to their purpose and proximity where possible.

The University of Wisconsin-Madison is responsible for obtaining WMO numbers for AWS sites and for providing Service ARGOS with calibration information for processing the data. The main reason for getting the AWS data into the GTS is to make sure that the data are available in near real time for all organizations operating in Antarctica. Of all the meteorological data in the GTS received by the Australian Bureau of Meteorology at Hobart, Tasmania, the AWS units provided more surface meteorological data than all the manned stations.

8. DATA AVAILABILITY

The data from our Automatic Weather Stations are available by anonymous FTP. The IP number is 144.92.108.169 (ice.ssec.wisc.edu). The login is "anonymous" (do not use the quotation marks), and the password is your email address. Once you have logged in, change to the pub subdirectory. A listing of our station locations, names, and ARGOS ID numbers is located in the file "biglist" in this subdirectory. It is meant to serve as a guide to our stations as their ID numbers

sometimes change. A complete guide for navigating the site may be found in the file Areadme.faq@.

Our three-hourly interval data for Antarctica are contained in the year subdirectories of pub/antrdr. The data have been corrected, i.e. an effort has been made to remove the bad data points. These data take longer to process, so the data for recent months are not available in this format. Within each of the year subdirectories of pub/antrdr, there are text files named "3hrlist??" (where ?? indicates the last two digits of the year). These files list what station's data are contained in which files. The file Areadme.updates@ in pub/antrdr contains information on updates and/or corrections to the data, and the file Areadme.3format@ contains file name construction information and format of the three-hourly data. The file "readme.mailinglist" contains information on joining a mailing list which distributes information on data updates and changes. To subscribe, send email to majordomo@ice.ssec.wisc.edu with the subject line left blank. In the message body, type Asubscribe three yourname@email.address@ (do no use quotation marks) and substitute your own email address for Ayourname@email.address@. The directory pub/summary/monthly contains printable text files of the paper data summary sheets. The format of the files can be found in the file "readme.sum" while updates and corrections to the data are located in "readme.sumupdates". The data are located in year subdirectories of pub/summary/monthly.

For those users who need more current information, we have created 10 minute interval data for each station. These data are located in year subdirectories of pub/10min/rdr. The data have been calibrated for the individual station instruments, but no other corrections have been made. The data are generally available up to and including the last full month of the current year. The year subdirectories also contain a text file named "namelist??" (where ?? indicates the last two digits of the year in question). These files list what station's data are contained in which files.

Several important readme files are located in pub/10min/rdr. The file "readme.5digit" contains information on the Siple Coast stations which have a different station identification. The file "readme.format" contains information on filename construction of the data, as well as file content and is a must for those unfamiliar with the data. The file "readme.updates" contains important information on changes/additions to the data, and the file Areadme.mailinglist@ contains information on joining a mailing list to receive notification by email of data changes and updates. To subscribe, send email to majordomo@ice.ssec.wisc.edu with the subject line left blank. In the message body, type Asubscribe ant yourname@email.address@ (do no use quotation marks) and substitute your own email address for Ayourname@email.address@. If you would like to see a list of all available mailing lists, please send email to majordomo@ice.ssec.wisc.edu with the subject line blank. In the message body type Alist@.

Our site is available 24 hours a day, 7 days a week. If you have questions or problems, send email to aws@ice.ssec.wisc.edu. We can also be reached by phone at (608) 265-2209 or fax at (608) 263-6738.By mail, please contact:

Linda M. Keller University of Wisconsin Dept. of Atmospheric and Oceanic Sciences 1225 W. Dayton St. Madison, WI 53706 USA

9. ACKNOWLEDGMENTS

This work is supported by the National Science Foundation, Office of Polar Programs, Grants 9303569 and 9419128 under the management of Dr. Bernhard Lettau of the National Science Foundation. Expeditions Polaires Francaises installs and maintains the AWS units from the Adelie Coast to Dome C. The British Antarctic Survey maintains the AWS units on the east side of the Antarctic Peninsula and south of Adelaide Island.